At least 12 people have been killed in a suspected US missile attack in a Pakistani tribal area bordering Afghanistan, officials say.

The incident in North Waziristan on Friday was the latest in a string of US raids on Pakistani soil which have raised tensions between Islamabad and Washington.

A local intelligence official said that as many as 16 foreign fighters had been killed, most of them Arabs. 

He said that the bombed house belonged to two Afghan refugees who had settled in Mohammad Khel, about 30km west of Miranshah, the main town in North Waziristan. 

Pakistani officials use the terms "Arab" and "foreigner" to describe fighters linked to al-Qaeda.

Al Jazeera's Kamal Hyder, reporting from Islamabad, said that while there had been reports of foreign fighters killed, the bodies found in the area were badly mutilated.   

There was no immediate confirmation of the attack from the Pakistani military or from the US-led forces in Afghanistan.

The attack in Mohammad Khel comes three days after a missile believed to have been fired by a US drone hit a suspected training camp in North Waziristan killing eight foreign fighters, according to officials.

Denial

The Pakistani military separately denied local reports that US helicopters and fighter jets from Afghanistan killed several people, including two women and a child, in another part of North Waziristan, earlier on Friday.
  
Local officials had initially claimed that a village lying just inside Pakistani territory was hit after US troops came under fire in Afghanistan's Khost province.

But the army said the incident happened in Afghanistan itself.
  
Major-General Athar Abbas, the chief Pakistani military spokesman, said: "Nothing of this sort happened in Pakistan's area."

"They [the US military] have informed us that they were carrying out an operation on the Afghan side of the border. There are no casualties on our side."

The US has stepped up attacks on pro-Taliban fighters in Pakistani territory since a new civilian government came to power in Islamabad in March.
  
Relations have also been strained by a raid by US special operations forces into Pakistan on September 3 which killed several residents.
  
Last week, Pakistani and US troops exchanged fire along the border after two US helicopters came under fire, a US military spokesman said.
     
Asif Ali Zardari, the Pakistani president, has vowed "zero tolerance" against violations of his country's sovereignty amid stepped up US missile attacks.